In recent years, a shape-of-endoscope detecting system has been adopted for detecting the shape of an endoscope inserted into a human body using magnetic-field generating elements and magnetic-field detecting elements, and displaying the detected shape on a display means.
For example, Japanese Unexamined Patent Application Publication No. 8-107875 has disclosed a system that detects the shape of an endoscope using magnetic fields and displaying the detected shape of the endoscope.
According to the patent publication, a plurality of magnetic-field generating elements disposed in the insertion portion of an endoscope, which is inserted into a human body, at predetermined intervals is driven in order to generate magnetic fields around the elements. Magnetic-field detecting elements disposed outside the human body are used to detect the three-dimensional positions of the respective magnetic-field generating elements. A curve continuously linking the positions of the magnetic-field generating elements is drawn, and a three-dimensional image representing a model of the insertion portion is displayed on a display means.
An operator or the like views the image to grasp the position of the distal section of the insertion portion inserted into a body or the inserted state of the insertion portion. This helps smoothly perform the work of inserting the insertion portion into a target region.
However, according to the related art, if the insertion portion is bent to form a loop having a small radius of curvature that is smaller than the interval between adjoining ones of the magnetic-field generating elements disposed in the insertion portion, the number of magnetic-field generating elements present in the looped portion of the insertion portion is so small that a streamlined shape similar to the actual shape of the looped insertion portion cannot be displayed.
An object of the present invention is to provide a shape-of-endoscope detecting system capable of highly precisely displaying the shape of an actual insertion portion despite a simple configuration.